The use of personal computers for processing provides several advantages to the user. For instance, since there is typically only one user, computer response time is predictable. Further, a personal computer may be portable, and is isolated from other users so that there is no worry about another user causing a system "crash".
Similarly, performing operations on a larger, or host computer provides certain advantages. For instance, on a host computer a central data base may be kept. In such a data base a large amount of data may be centrally managed assuring that all users of the data base have access to valid, "up-to-data" information. It is desirable to design systems which utilize both personal computers and a host computer and which profit from the advantages of each type of computer.